The purpose of this investigation is to determine the effectiveness of a controlled physical activity program on the status of coronary heart disease risk in children. Three hundred and eighty-four boys and girls, ages 6 through 8 years will be assigned to either a physical activity group or control group. Each child will be screened at the beginning of the school year and at the end for obesity, EKG abnormalities, elevated blood lipids and hypertension. In addition, surveys will be completed to assess family medical history of CHD and behavior and beliefs towards physical activity. Densiometric techniques will be employed for determination of body composition. A graded exercise stress test will be utilized for EKG screening and a blood lipid analysis will be performed to screen for hyperlipoproteinemia. The physical activity program will consist of four, 30-minute sessions each week for the entire school year and will emphasize skill acquisition and high intensity physical activities.